Testing devices



Nov. 15, 1955 Filed Feb. 29, 1952 C. T. ZAVALES TESTING DEVICES 5 sheets-sheet 1 T0 LINE VOL 779655 GAIN SWEEP CONTACTS Focos START INTENSIT( vDELAY 94 fiez L vf-42 W50/wwe@ l INVENTOR C. 7': ZWl/HZE' H 'vf-FP TIME ATTORNEY Nov. l5, 1955 c. T, ZAVALES 2,724,073

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ATTORNEY Nov. 15, 1955 C. T. zAvALEs 2,724,073

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ATTORNEY United States Patent 'ifV 2,724,073 TESTING DEVE Charles T. Zavales, New York, N. Y., as'signor to F-R Machine Works, Woodside, Long Island, No Y., a irm Application February 29, 1952, sonni No. 274,231 Claims. (Cl. 3115-4-29)v This invention relates primarily to testingpparatus and more' particularly to apparatus' for checking traits'ient phenomena. The' apparatus of this invention finds especial utility in the iields of X-r'ys and electric spot welding. Y i

In the X-ray field, for example, there are two problems,

calor electronic timers" tvniollr inev have been irse/d. With such! accurate information "de available' by flie use of this' invention,` proper measures :nay ue taken with the Xer'ly' mechanismso' that eiipdsure time and piiasiigi may e accurately seti and r'e'set. Witl'r the' novel apparatus, it also is* possi-ble t'o che'cl line voltage drop under' load, to cheek the operationof' electron-ie or mechantontl onuiarn'pere stabilizers, to` check! valve tube operation, to clieck filamenti v'olt'age stabilizer operation, and to check phototi'r opration, etc. A K* r l According to this invention, 1 have provided a novel apparat-'us which may be emp-loy'edfor making ll of the various: tests heretofore'4 setl forth, as' weil as ot'hfe'rs,l in al very' sinip'Ie and expeditions ninn'ner'; Tite apparatus or this invention includes' a cath'ode'-Y 'y tube having" a persistent screen enabling visuali on of -transient phe'noinen-av for periods up toE approximately 2' minutes after the phenomena has occurred, and alsoY includes a manually operable start switch for simultaneously start'- ing the phenomenon andthe sweep of the elfect'r'oril Beam of the cathode tube. The' apparatus also includes a dely circuit for ontrouing the deiav between the finie the start" switch is actuatedr andE thfe tirne the' sweepiisin' i'ated. This apparatusV embodying said features is smallajndcomp'ac't and* is char'ct'eried a' novel r'tigg'ed, sii'ripl'ied andcmp'aratively reasonably'pricedz circuitry; In' addition, the' sweep oir'oiiit'pet' se isnovei'. v A

The apparatus of thisA invention, aswell sfthe typical test potternsunder' various oonditions-i of employment of the invention; are" shown ink tii-e following drawings, wherein: n

Fig'. il is a diagrammatic illustr'ti'onlof a typical lclonnection of novelv apparatus with an* X-rav eiiit to Be tested. Y V Y Fig. 2l is a wiring dia'grarrlA of tl'ie invention,

Fig. f shows thev linearity of operation of the sweep circuit. v l' Fig; 4--Fig1 1"@l illustrate various test: patterns" visually ohservable onl the persistent scre'e'rot" the cathode ray tube when the inventioniserplyed'f making particu lr tests onY-ray equipment. Y Y

2,724,073' Patente-d Nov. 15, 1955 2 in'. This lil/l 10 iS the input for the pW' supply 1'2 shown diagrammatic'ally. The power supply 12 has a pir Of Output lrileiit POWE' Supply lilies 13 f lie cathode of cathode ray tube 14;- output power supply lines 15 and 16 are respectively maintained at "2-5Q0 and l+250() to provide accelerating voltages for the `cathode ray tube 14. Filament power supply lines 17 nergize the filament of Va sweep generating tube `18 arid piower supply lines 19, 20 and 21 respectively maintained at approximately 0`, +135 and 135 volts, for th sweep generator and delay circuits. A number of relays 9', `2v2 and 23 are arranged in parallel. In series with said relays and said input 10 is a normally open switch 24; The noi/el sweep circuit of this invention comprises the conductor 21 in series with a variable resistor 103 connected tothe cathode of the sweep' generating tube 28,A which is essentiaily a pentode with grids 25, 24S a'n'd 27 and plate 2,9. The grid` 25, which is the control grid, is connected to the conductor 21. The grid 26, which is a screen grid, is connected to the conductor 20 through resistor 30 which serves to set the ,screen voltage. The grid' 27 nis the suppressor grid and is connected to the cathode 28 of the tube 18. The anode 29 is connected to one c onta'ct 31 of a double' pole double throw relay switch which is part of relay 22. Line" 20`1`s' connected to Contact 32 df said double ple double throw lay Switch. Clifrent limiting resistor' 33 is connected in series with line 20 arid Contact 34 Of said du'bie fioler doubl hfW switch. A current limiting resistor 35 is connected in series with line 21 and Contact 36 of said double pole d'oub'le throw switch.r The corinfrion 37 of said` switch is connected at' its midpoint 3S tot one side of" a' condenser 39 arid the other` side of the condenser is cnnc'c'sted'v t'o ground through acurret limiting resistor 40. A common' arm 41 of said switch`A` is connected at its midpoint to one side of a" similar condenser 4i also in ttrn connected tothe ground through resistor 40. A pair ofcondu'ctors' 45f` and 46; are connected' tothe outside plates ofthe c'ondeiiser's' 39 and 42 and serve asl the output of thisl sweep circuit r generator. n Y Y m The delay circuit 50 includes' cotz'ictsl 51 of a normally openswitch 52 manually operable by a' push button hereinafter described', and also a pair' of" contacts 61 normally closed By aI bar of said switch. O`r1e of thecontct's 51 s connected to line 20", and the other Contact 51 aridl one of the contacts 6'1' are'coiinec'te'd toone'- eridof the' operating coil 55 o'f a` D'. C. relay' which in turn is" connected to the anode 56 of a cold cathode thyratrn 5:7;` The cathode 58 of the th'yra'tron' is connected to line 19 which is atze'ro potential5 and which isy grounded through anormal-ly closed' switch 59; part' of' thenrelay 97%. A contact of theA switch 59` is also in series with a timing condenser 60 which' is inf series with flic' other contact ,Q1 of the switchl 52; Thev thyrat'ron has acon'trol grid 621m series wit-ha current limiting resistor 63 and timing resistor 64 andt-iming'resistor 65', which in turn is connected to those contacts 5T and 6-1 connected to coil 55. A manually operable singlcf poledouble'throw switch 6"'6 has one' end connected toa'contact 67 in'tu'ijn connected to" the' ridpoint` of thef resistors 63: and' 64` while the other contacts- 69 and 70 are respectively connected totiming resistor'A 65 and tothe tin-ling condenser 60 Shu'ntedaclr'os's" th'e coil 55 and thyrt'r'on' 57'Vis' a discharge resistor 72.Y

The4 cathode ray tube" circuit' includes af filament' 73, control and-` accelerating electrodes' 74, 73? and T6, vertical deectin'g plates 77 and horizontal dellectingplates' 78 and a post accelerating anode 7 9. The post` accelerate ing anode 79 isY connected'tothe" litielithroughfa'current limiting. resistor Si). A voltage divider 83',- co'r'ittprising'I a number of resistors' of diier'entivalues', is connected tol line 1'5i and to ground. The control grid T4is" connected' tol line 15. The accelerating electrode is connected to apotentiometer 11M which is part of resistor 83 and the other accelerating electrode 76 is connected to ground and the cathode 73 is connected to a suitable tap $5 of the resistor 83 and is also connected to one terminal 36 of a normally open switch, part or" relay 23. The other contact 87 of said Switch is connected through an intensity control resistor 83 in turn connected to the line 15. The vertical deflecting plates 77 are connected respectively to ground through grid leal; resistors @l and 592. One of the vertical dellecting plates 77 is connected directly to the input terminal 93 while the other deliecting plate 7'7 is connected to an arm 94 of a potentiometer 95, one end of which is connected to the terminal g3 and the other end is connected to a terminal 96. Ther horizontal .dellecting plates '78 are connected to the output terminals and i6 of the sweep generating circuit. Normally open contacts 1G@ which operate in tandem with switch S2 are connected to the terminals 161 and 1532, which are the external control terminals.

The mode of operation is brietly as follows: First the switch 11 is closed so that the electric current supply 10, for example, 117 volt 50--60 cycles, is fed to the power supply 12. immediately thereafter the lament 73 of the cathode ray tube 14 and the lila-ment of the sweep generating tube 1d come to temperature, and the power supply 12 produces the voltages indicated on the lines 15, 16, 19, 2@ and 2l. ln this manner, high voltage is applied to the electrodes of the cathode ray tube 14. Suitable voltages for the individual electrodes of said tube 14 are determined by the relative values of the voltage divider 83. The potential between the grid and the cathode of tube 14 is so chosen as to make the grid 74 of tube 11% sutliciently negative to prevent electrons from reaching the screen of tube 14. This makes the cathode ray tube 14 inactive at this time because the electron beam is thus effectively cut off. However, the beam may be made visible by reducing the magnitude of voltage between the grid 74 and cathode 73. The normally open contacts S6 and 87 and resistor 8S are so arranged to reduce the negative bias between the grid and the cathode so that the beam may become visible when the relay 23 is operated to close the contacts 86 and 37. The value of resistor 38 determines the intensity of beam current which flows in the tube 14 when the contacts 86 and 87 are closed.

In addition, as soon as switch 11 is closed the following happens in the sweep circuit: Condenser 39 is charged to plus 135 Vvolts through line 2,0, resistor 33, closed switch 37 to one side of the condenser 39 and from the other side of the condenser 39 through resistor 4d to ground and through closed switch 59 to line 19 which is at zero potential. Condenser 42 is charged to minus 135 volts through line 21, resistor 35, closed switch 41, to one side of the condenser d2, and from the other side of the condenser 42 to the resistor 40 to ground through the closed switch 59 to the line 19 at zero potential. The total voltage across the series circuit of the condensers 39 and 42 is 270 volts. This arrangement effectively provides a cententapped condenser' arrangement -for the deecting circuit so that differences in potential between the plates 73 is 270 volts while the potential dllerence at the midpoint between those plates is approximately-zero which is for the prevention of defocusing of the electron beam as it may be deflected from right to left in tube 14 by the horizontal plates 73.

lThe invention may be employed in a number of diterent ways. It is so flexible that it is possible to operate it in a number of ways. It may be set so that there will be no delay between operations in another way it may be set so that there will be a time delay between sequence of operations. When no time delay sequence of operation is desired, the switch 65 is disposed in the out position so that the time condenser 69 is completely out of circuit and the time delay resistor dfi is Shunted out. (As shown in Fig. 2.)

come into contact.

Switch 52 is manually operated whereupon one of the bars thereof closes the contacts 1% to start the sequence of the phenomena to be studied when contacts 1551 and 102 are connected to the device to be tested. Simultaneously another bar of that switch opens the normally closed contacts 61 and closes the contacts 51.

When the contacts 51 are thus closed, plus 135 volts is Y supplied by line 211, through resistor 65 through switch ad through resistor 63 to the grid 62 of the cold cathode thyratron whereupon ionization occurs and the tube becomes conductive instantly. Then current ows through the relay coil 55 thereby closing the switch of relay 24 whereupon the coils of relays 22 and 23 are simultaneously energized. Coil of relay 9 is energized, to open the normally closed switch S9 and at the same time relay 7a3 is energized to close the normally open contacts Se and 87. The switch 59 is opened to break the connection between ground and line 19 which is at zero potential. When the contacts Se and 87 are closed the negative bias on grid 74 is reduced so that the electron beam is permitted to reach the screen of tube 17 whereupon it becomes visible.

Energization of relay 22 causes swinging of the switch elements 41 and 37 away from contacts 3d and 36, whereby the condensers 39 and 4Z are ont ot charge with respect to the power supply 12 and at the same time the elements 37 and 41 respectively are coupled to contacts 31 and 32. This connects the positive side of condenser 39 to the anode 29 of tube 18 and the negative side of condenser 42 to the power supply line 20. The voltage between the horizontal deilecting plates 7S, which is the sum of the voltages of the two condensers 39 and 42, is shown diagrammatically in Fig. 3, and occurs between those plates '7S the instant that 37-31 and 41-32 As soon as this occurs, the current starts to tlow through the tube 18 which is a constant current tube. The magnitude of current tiowing through said tube is controlled by the variable resistor 103. The current ows through said tube 18 and is furnished by the condensers 39)V and 42 and because of this the voltage between these condensers will fall ot at a linear rate as shown in Fig. 3. This action continues until the voltage across the condensers reaches a value equal to the initial value, except for a reverse in polarity as shown in Fig. 3. The slope of the linear discharge line represents the sweep time. By setting the variable resistor 193, there is provided a ready means for controlling the sweep time, it being observed that the length of the linear discharge line as shown in Fig. 3 may be lengthened or shortened depending upon the setting of that resistor.

The voltages of the condensers 39 and 42 are always equal to each -other and of opposite polarity, are impressed upon the deecting plates 78 which control the travel of the electron beam on the screen of the tube 14. Therefore, the potential between plates 73 is varied at said uniform rate which is linear, so that sweep of said beam on said screen is at a linear rate.

lAfter the sweep or" the beam on the persistent screen ot the cathode-ray tube oscillograph 14 has been completed, a complete cycle of operation has occurred. The operator now releases the switch 52 so that the elements 37 and 41 automatically move away from contacts 31 and 32 respectively to break the condenser discharging and recharging circuit. After moving from contacts 31 and 32 respectively, said elements 37 and 41 automatically rnove to contacts 34 and 36 respectively to their original position as shown in Fig. 2 to again make the original condenser charging circuit as shown in said gure. When the condenser chargingrcircuit is again made, the condensers 39 and 42 are directly across the centertapped direct current power supply lines 20 and 21 whereupon they are charged almost immediately to voltages of the ,original value and polarities. Y

The circuit components may he so chosen that the sweep time may be varied over fairly wide limits, namely 1/200 of a second to approximately 2 seconds, for example. In this manner, it is also possible to obtain a wide range of time sweeps.

If it is desired to have a delayed operation, which is a predetermined time delay between the time that the contacts 101 and 102 are closed and the time that the ,beam becomes visible, that is possible with this invention. Por this purpose the switch 66 is actuated to move it from contact 69 and into contact 70, whereuponthe time condenser 60 and resistor 64 are now in circuit. In this case, the switch 52 is actuated to connect the 135 volt line 20 to closed contacts 51, through resistors 65, 64 and 63 to the grid 62 of the thyratron 57. When these contacts 51 are closed and contacts 61 are simultaneously opened, timing condenser 60 is prevented from being discharged through resistor 72 to ground and condenser 60 starts to charge from line 20 through contacts 51, resistor 64, variable timing resistor 64, switch 66, condenser 60, to ground through line 19 and its rate of chargeis based upon the setting of the variable resistor 64. When the voltage at the condenser 60 reaches a predetermined value, the thyratron tube 57 becomes ionized and current ii'ows through the relay 55 closing switch 24 whereuponA the operation thereafter is as before described. The time delay between the time the contacts 101 and 102 are closed and switch 2,4 is closed is thus controlled and dependent upon the condenser 60 as controlled by the variable resistor 64.

The device whose voltage phenomena under study is connected to contacts 93 and 96 which are in turn connected through potentiometer 95 to the vertical deecting plates 77 of tube 14. The magnitude of the voltage of tube 14 is controlled by the variable potentiometer 95.

A typical manner of use of the invention is herein set forth merely by way of illustration and not by way of limitation, because it is obvious to those in the art of the many other ways in which this invention might be employed. One such apparatus which may be subject to tests is an X-ray apparatus of a conventional design as shown in Fig. 1. This apparatus comprises a conventional auto-transformer 200 connected to input line 201 through switch 202. A high voltage transformer 203 has one side of its primary connected to auto-transformer 200 through line 204, and the other side of the primary is connected to said auto-transformer by line 205 through a normally open switch 206. Said switch 206 is operated by a conventional X-ray timer 207 receiving its supply from line 201 and having a conventional, normally open push button switch 208 for starting and controlling the exposure time of the X-ray tube which initiates the exposure, and which exposure in turn is controlled by the timer. An X-ray tube 210 is connected across the secondary of the high tension transformer in the conventional manner as shown, and including resistor 211 in the midpoint circuit of the high tension transformer. Assuming that it is desired to check accurately, the timer of an X-ray apparatus, the example of which was hereinbefore described. In that case, contacts 101 and 102 are connected to the respective contacts of the normally open switch 208 of said timer and contacts 93 and 96 are connected to the lines 204 and 205 which are the terminals of the primary of the high tension transformer. If the timer in question is of the type that does not have an operating time delay, for example, a synchronous timer, the delay switch 66 is located at the out position as shown. With the connections as described, operation of the start push button 52 will close contacts 51 and also contacts 100, whereby there is closed the timer push button switch within the X-ray control to initiate the X-ray exposure and at the same time the sweep beam boosting circuit within the test device will become operable, as hereinbefore described. The duration of the X-ray exposure, which will be dependent upon the setting of the timer in the X-ray equipment, will become visible and persist on the screen of the cathode ray tube 14 as the number of power frequency impulses that are across the primary of the high tension transformer. If the timer isset for liso 0f asec= ond the image which persists on the screen of the tube 14 for a suticient length ofti'me` to be accurately observed by the tester, is that shown in the left hand view of Fig. 4,l and if the image is that Shown in the right vhand View of Fig. 4, with the timer set at en of a second, this indicates that the timer is in proper condition. AWhen a mechanical'impulse timer is to be tested in such a circuit then the switch 66 is at the in position as shown so that there is a time delay in the operation of the test device of the invention. For impulse timer testing where close timing contacts must be made at the zero point of the voltage wave form, the test device provides the most valuable means of determining this condition. The ideal condition is that shown in the left hand view of Fig. 6, while the condition which sometimes exists and must be corrected is that shown on the right hand side of said figure. The wave form of the'` device may be obtained by employing this invention in conjunction with that particular type of timer. The line voltage regulation charactenstic may be quickly determined by connecting contacts 93 and 96 directly across the line 201, as shown in Fig. 1 in dotted lines. A particular wave form showing excessive line voltage drop which is readily discernible by employing this invention is shown in Fig. 5. There is no known easy way of doing this now without very elaborate and costly laboratory equipment. The performance of electronic milliampere stabilizer, valve tube, lament voltage stabilizers, and milliampere characteristics without stabilizers may be ascertained as shown in Figs.

-10 respectively, readily by connecting a viewing resistor 211 into the midpoint circuit in the secondary of the high tension transformer 203, and visualizing the above mentioned equipment performance the input terminals 93 and 96 are connected across the viewing resistor 211.

I claim:

1. ln combination with a persistent screen cathode ray oscillograph having a pair of deecting plates, of a sweep circuit comprising a pair of centertapped condensers connected across said plates, means for charging said condensers to voltages of equal values and of opposite polarities, means for discharging said condensers at a linear rate and for recharging said condensers at the same rate to voltages equal to and of opposite polarities to the voltages of said respective condensers at the beginning of said discharging for varying the voltage at each of said plates at a linear rate from its value and polarity to the same value and opposite polarity.

2. In combination with a persistent screen cathode ray oscillograph having a pair of deecting plates, of a sweep circuit comprising a pair of centertapped condensers connected across said plates, means for charging said condensers to voltages of equal values and of opposite polarities, means for discharging said condensers at a linear rate and for recharging said condensers at the same rate to voltages equal to and of opposite polarities to the voltages of said respective condensers at the beginning of said discharging for varying the voltage at each of said plates at a linear rate from its value and polarity to the same value and opposite polarity, said last mentioned means including only a single constant current tube and means for varying the magnitude or current How through said tube for controlling the rate of said discharging and recharging of said condensers for controlling the sweep time.

3. In combination with a persistent screen cathode ray oscillograph having a pair of dellecting plates, of a sweep circuit including a pair of condensers, means connectable to said condensers for charging said condensers to equal voltages of opposite polarities and said condensers connected to said plates for providing equal voltages of opposite polarities to said plates, means for connecting said rst mentioned means to said condensers, means connectable to said condensers for discharging said con densers at a linear rate and for recharging said condensers at the same rate to voltages equal to and of opposite polarities to the voltages of the respective condensers at thelbeginning of said discharge, said last mentioned means including only a single constant current tube and a variable resistor for controlling the magnitude of current ow through said tube for controlling the linear rate of. said discharging and recharging of said condensers for controlling the sweep* time. l

l 4. In combination with a persistent screen cathode ray oscillograph having d ay pair of deiiecting plates, of a sweep circuit including a pair of centertapped condensers connected across said plates, a charging circuit for said condensers, said circuit including means for making and breakingfsaid circuit, Vsaid condensers and a source of directcurrent power supply for charging said condensers Ito voltages of equal. values andV opposite polarities, a

discharging and recharging circuit for discharging said condensers at a linear'rate and recharging them at the same rate to voltages equal to and of opposite polarity to their voltages at lthe beginning of said discharging,

said last mentioned circuit including in series said conoscillograph having a pair of deflecting plates, of a sweep circuit comprising a pair of centertapped condensers connected across said plates, means for making a circuitbetween said condensers and a source of direct eurrent supply to charge said condensers to voltages of equal values and of opposite polarities and for breaking said circuit, only a single constant current tube and means fon making a circuit between said constant current tube, said condensers and a source of direct current Vsupply to discharge said condensers at a linear rate and to recharge said condensers at the same rate to voltages equal to andof opposite polarities to the voltages of said respective condensersfat the beginning of said discharge for varying the voltage at a linear rate at each o5 said plates from its value and polarity at the beginning Vof said discharge to the same value and opposite polarities.

References Cited in theV iile of this patent Fyler 2---- Ian. 4, 1949 

